The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea
The caldera-forming eruption of the Aniakchak volcano in the Aleutian Range on the Alaskan Peninsula at 3.6 cal kyr BP was one of the largest Holocene eruptions worldwide. The resulting ash is found as a visible sediment layer in several Alaskan sites and as a cryptotephra on Newfoundland and Greenl...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-04-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/13/303/2017/cp-13-303-2017.pdf |
| _version_ | 1818571810346631168 |
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| author | C. Pearce A. Varhelyi S. Wastegård F. Muschitiello N. Barrientos M. O'Regan T. M. Cronin L. Gemery I. Semiletov J. Backman M. Jakobsson |
| author_facet | C. Pearce A. Varhelyi S. Wastegård F. Muschitiello N. Barrientos M. O'Regan T. M. Cronin L. Gemery I. Semiletov J. Backman M. Jakobsson |
| author_sort | C. Pearce |
| collection | DOAJ |
| description | The caldera-forming eruption of the Aniakchak volcano in the Aleutian Range
on the Alaskan Peninsula at 3.6 cal kyr BP was one of the largest Holocene
eruptions worldwide. The resulting ash is found as a visible sediment layer
in several Alaskan sites and as a cryptotephra on Newfoundland and Greenland.
This large geographic distribution, combined with the fact that the eruption
is relatively well constrained in time using radiocarbon dating of lake
sediments and annual layer counts in ice cores, makes it an excellent
stratigraphic marker for dating and correlating mid–late Holocene sediment
and paleoclimate records. This study presents the outcome of a targeted
search for the Aniakchak tephra in a marine sediment core from the Arctic
Ocean, namely Core SWERUS-L2-2-PC1 (2PC), raised from 57 m water depth in
Herald Canyon, western Chukchi Sea. High concentrations of tephra shards,
with a geochemical signature matching that of Aniakchak ash, were observed
across a more than 1.5 m long sediment sequence. Since the primary input of
volcanic ash is through atmospheric transport, and assuming that bioturbation
can account for mixing up to ca. 10 cm of the marine sediment deposited at
the coring site, the broad signal is interpreted as sustained reworking at
the sediment source input. The isochron is therefore placed at the base of
the sudden increase in tephra concentrations rather than at the maximum
concentration. This interpretation of major reworking is strengthened by
analysis of grain size distribution which points to ice rafting as an
important secondary transport mechanism of volcanic ash. Combined with
radiocarbon dates on mollusks in the same sediment core, the volcanic marker
is used to calculate a marine radiocarbon reservoir age offset Δ<i>R</i> = 477 ± 60 years. This relatively high value may be explained by the major
influence of typically <q>carbon-old</q> Pacific waters, and it agrees well with
recent estimates of Δ<i>R</i> along the northwest Alaskan coast, possibly
indicating stable oceanographic conditions during the second half of the
Holocene. Our use of a volcanic absolute age marker to obtain the marine
reservoir age offset is the first of its kind in the Arctic Ocean and
provides an important framework for improving chronologies and correlating
marine sediment archives in this region. Core 2PC has a high sediment
accumulation rate averaging 200 cm kyr<sup>−1</sup> throughout the last
4000 years, and the chronology presented here provides a solid base for high-resolution reconstructions of late Holocene climate and ocean variability in
the Chukchi Sea. |
| first_indexed | 2024-12-14T18:49:13Z |
| format | Article |
| id | doaj.art-94cbfcfad3aa4b5da0605472311dbfae |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-14T18:49:13Z |
| publishDate | 2017-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-94cbfcfad3aa4b5da0605472311dbfae2022-12-21T22:51:18ZengCopernicus PublicationsClimate of the Past1814-93241814-93322017-04-0113430331610.5194/cp-13-303-2017The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi SeaC. Pearce0A. Varhelyi1S. Wastegård2F. Muschitiello3N. Barrientos4M. O'Regan5T. M. Cronin6L. Gemery7I. Semiletov8J. Backman9M. Jakobsson10Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, SwedenDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, SwedenDepartment of Physical Geography and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, SwedenDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, SwedenDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, SwedenDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, SwedenU.S. Geological Survey, Reston, Virginia 20192, USAU.S. Geological Survey, Reston, Virginia 20192, USATomsk National Research Polytechnic University, Tomsk, RussiaDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, SwedenDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, SwedenThe caldera-forming eruption of the Aniakchak volcano in the Aleutian Range on the Alaskan Peninsula at 3.6 cal kyr BP was one of the largest Holocene eruptions worldwide. The resulting ash is found as a visible sediment layer in several Alaskan sites and as a cryptotephra on Newfoundland and Greenland. This large geographic distribution, combined with the fact that the eruption is relatively well constrained in time using radiocarbon dating of lake sediments and annual layer counts in ice cores, makes it an excellent stratigraphic marker for dating and correlating mid–late Holocene sediment and paleoclimate records. This study presents the outcome of a targeted search for the Aniakchak tephra in a marine sediment core from the Arctic Ocean, namely Core SWERUS-L2-2-PC1 (2PC), raised from 57 m water depth in Herald Canyon, western Chukchi Sea. High concentrations of tephra shards, with a geochemical signature matching that of Aniakchak ash, were observed across a more than 1.5 m long sediment sequence. Since the primary input of volcanic ash is through atmospheric transport, and assuming that bioturbation can account for mixing up to ca. 10 cm of the marine sediment deposited at the coring site, the broad signal is interpreted as sustained reworking at the sediment source input. The isochron is therefore placed at the base of the sudden increase in tephra concentrations rather than at the maximum concentration. This interpretation of major reworking is strengthened by analysis of grain size distribution which points to ice rafting as an important secondary transport mechanism of volcanic ash. Combined with radiocarbon dates on mollusks in the same sediment core, the volcanic marker is used to calculate a marine radiocarbon reservoir age offset Δ<i>R</i> = 477 ± 60 years. This relatively high value may be explained by the major influence of typically <q>carbon-old</q> Pacific waters, and it agrees well with recent estimates of Δ<i>R</i> along the northwest Alaskan coast, possibly indicating stable oceanographic conditions during the second half of the Holocene. Our use of a volcanic absolute age marker to obtain the marine reservoir age offset is the first of its kind in the Arctic Ocean and provides an important framework for improving chronologies and correlating marine sediment archives in this region. Core 2PC has a high sediment accumulation rate averaging 200 cm kyr<sup>−1</sup> throughout the last 4000 years, and the chronology presented here provides a solid base for high-resolution reconstructions of late Holocene climate and ocean variability in the Chukchi Sea.http://www.clim-past.net/13/303/2017/cp-13-303-2017.pdf |
| spellingShingle | C. Pearce A. Varhelyi S. Wastegård F. Muschitiello N. Barrientos M. O'Regan T. M. Cronin L. Gemery I. Semiletov J. Backman M. Jakobsson The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea Climate of the Past |
| title | The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea |
| title_full | The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea |
| title_fullStr | The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea |
| title_full_unstemmed | The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea |
| title_short | The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea |
| title_sort | 3 6 ka aniakchak tephra in the arctic ocean a constraint on the holocene radiocarbon reservoir age in the chukchi sea |
| url | http://www.clim-past.net/13/303/2017/cp-13-303-2017.pdf |
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